Kiwis are flocking to get immunised against a "killer flu" strain in unprecedented numbers this flu season.

More than a million New Zealanders have had their flu vaccinations so far this year, a good 250,000 more than this time last year and 350,000 more than in 2009.

Associate Health Minister Jo Goodhew said many in the healthcare sector were commenting that this was the highest demand they had seen, even higher than during the 2010 pandemic.

It comes after fears that a killer flu which led to the death of 64 children in the United States could hit New Zealand's shores this winter.

By April 18, an unprecedented 75,510 vaccinations had been given out in the Waikato, nearly 4000 more than in the same period last year.

And less than a week later, that number had already surpassed 80,000 - a number that health professionals expect will continue to rise.

The Waikato District Health Board's clinical nurse co-ordinator in immunisation, Kim Hunter, said thanks to global monitoring and information sharing, New Zealand was able to immunise against the specific killer strain coming in from overseas and expected many others would be lining up for it as the season progresses.

"You always get that initial first rush, and as time goes on, those people who have been sitting on the fence start to hear about reports of cases and hospitalisation and whatnot, and they start coming in," she said.

"We've already seen an excellent uptake this season and I think concerns about the flu strains from the northern hemisphere are helping to drive that, which I think is actually really wise. We're already seeing cases of influenza here now so you can never be too careful, or too early."

Radius Medical's chief executive Navin Rajan said many more people than usual were coming in for vaccinations - and for much the same reason.

"We've had heaps, heaps of people. I think people are hearing about the bird flu and all these problems overseas and that's scaring them and they're taking every step they can to protect themselves," Dr Rajan said. "We're very happy to see people are doing that, it's great to see."

Vaccinations are free from a doctor or nurse for New Zealanders at high risk of complications - pregnant women, people aged 65 and over, and for people of any age with long-term health conditions.